The Nematoda phylum consists of Nematodes, which are parasitic roundworms that live in intense environments and most ecosystems.[1] Roundworms are part of the Ecdysozoa group, which also includes arthropods such as crustaceans, spiders, and insects. The members of this group are also protostomes, which means that roundworms have bilateral symmetry. Roundworms are known to live in hot springs and arctic ice. They can also strive in different ecosystems, such as mountaintops and deep ocean trenches.[2]
A large mass of roundworms.
Kingdom: Animalia Phylum: Nematoda
Anatomy Roundworms vary in sizes from less than a millimeter to over 10 meters.2 Worldwide, there are about 15,000 different species of roundworms living on earth.[3] Roundworms have cylindrical bodies with a blunt head and tapered tail. They contain no circulatory system, respiratory system, or organ system, but they do have a complete digestive tract. The complete digestive tract consists of a mouth, pharynx, intestine, and anus. A complete digestive tract is when there are two openings (mouth and anus) to a complete digestive tract.[4] A roundworms food travels through the complete digestive tract. Roundworms food consists of plant matter, algae and bacteria.2 Roundworms have a hydrostatic skeleton, which is what supports and controls an animal’s movements. This is very important because without it most animals would not be able to function efficiently. A hydrostatic skeleton has walls that are two layers of muscles. Inside of the skeleton is incompressible fluid. When pressure is put on the fluid by the muscles, the animal is able to move.[5] Roundworms also have a tough exoskeleton known as a cuticle. This cuticle is made of chitin and whenever a roundworm grows, it sheds it cuticle. A roundworm sheds around four times before it reaches its full development.2 When the cuticle is shed, the body of the animal becomes very soft. This makes it easier for its predators to catch it. The skin of the animal stays soft until its new skeleton is fully grown and turns hard.2 The cuticle lies over a layer of muscles that makes a roundworm able to bend its body side-to-side rather than crawling like most types of worms. The muscle makes the roundworms movements more whip-like. A roundworm is labeled as a pseudocoelomate because it is not completely lined by muscle.2 Members of the Nematoda phylum are pseudocoelomate, meaning that they have a fluid filled body cavity that surrounds the gut.[6] Parasitic Species Roundworms are known to infect other species of plants and animals around the world. In many farming communities there is a loss of crops due to the infections from roundworms. They can also affect other species, such as humans. Most of these infections come from species of roundworms, such as the hookworm, pinworm, and Guinea worm.[7] A person can be infected by a hookworm by simply walking barefoot on contaminated soil.7 The hookworm goes into the small intestine of a person and releases larvae that matures and penetrates the human skin.[8] Most of these infections take place in tropical or subtropical climates.7 People who are infected sometime do not show symptoms, but other time they can suffer gastrointestinal symptoms. In some cases, people can suffer blood loss which lead to anemia, or protein loss. Though this infection is very serious, it is treatable with the correct medication.6 A Pinworm is a small, white parasite that infects the large intestine. This worm infects its host animal by feeding off of the hosts nutrients. Also, if an animal swallows a Pinworm egg, picked up from infected surface, it can be contaminated with Pinworms. Pinworms can be spread very easily just, but there are many treatments.[9] The Guinea worm is a painful disease that affects a person when they drink contaminated water.[10] The larvae of a Guinea worm grow inside a person’s gut and connective tissues.7 The worm can grow to be over a metre long, and after a year the worm winds its way through the body. It then exits the body through the skin, leaving a painful blister behind.8
Nematoda Phylum Systematic Adenophorea
Enoplia
Enoplida
Isolaimida
Mononchida
Dorylaimida*
Stichosomida
Triplonchida*
Chromadoria
Araeolaimida
Chromadorida
Desmoscolecida
Desmodorida
Monhysterida
Secernentea
Spiruria
Spirurida
Ascarida
Camallanida
Drilonematida
Diplogasteria
Diplogasterida
Tylenchida*
Above is the list of classes, sub-classes, and orders of the Nematoda, in a classical morphology-based classification system. As shown, there are five sub-classes and nineteen orders. In order to see which ones have plant-feeding genera, there are (*).[11] Evolutionarily Successful The Nematode is the most successful of several pseudocoelomate phyla. It is found in nearly every habitat including marine, freshwater, terrestrial, free living, and parasitic. They have populated every damp habitat that has been studied. Nematodes can be any of carnivores, herbivores or parasitic, and are found almost everywhere on earth. The Nematoda phylum is very abundant and ecologically important.[12]
The Nematoda phylum consists of Nematodes, which are parasitic roundworms that live in intense environments and most ecosystems.[1] Roundworms are part of the Ecdysozoa group, which also includes arthropods such as crustaceans, spiders, and insects. The members of this group are also protostomes, which means that roundworms have bilateral symmetry. Roundworms are known to live in hot springs and arctic ice. They can also strive in different ecosystems, such as mountaintops and deep ocean trenches.[2]
Phylum: Nematoda
Anatomy
Roundworms vary in sizes from less than a millimeter to over 10 meters.2 Worldwide, there are about 15,000 different species of roundworms living on earth.[3] Roundworms have cylindrical bodies with a blunt head and tapered tail. They contain no circulatory system, respiratory system, or organ system, but they do have a complete digestive tract. The complete digestive tract consists of a mouth, pharynx, intestine, and anus. A complete digestive tract is when there are two openings (mouth and anus) to a complete digestive tract.[4] A roundworms food travels through the complete digestive tract. Roundworms food consists of plant matter, algae and bacteria.2
Roundworms have a hydrostatic skeleton, which is what supports and controls an animal’s movements. This is very important because without it most animals would not be able to function efficiently. A hydrostatic skeleton has walls that are two layers of muscles. Inside of the skeleton is incompressible fluid. When pressure is put on the fluid by the muscles, the animal is able to move.[5] Roundworms also have a tough exoskeleton known as a cuticle. This cuticle is made of chitin and whenever a roundworm grows, it sheds it cuticle. A roundworm sheds around four times before it reaches its full development.2 When the cuticle is shed, the body of the animal becomes very soft. This makes it easier for its predators to catch it. The skin of the animal stays soft until its new skeleton is fully grown and turns hard.2
The cuticle lies over a layer of muscles that makes a roundworm able to bend its body side-to-side rather than crawling like most types of worms. The muscle makes the roundworms movements more whip-like. A roundworm is labeled as a pseudocoelomate because it is not completely lined by muscle.2 Members of the Nematoda phylum are pseudocoelomate, meaning that they have a fluid filled body cavity that surrounds the gut.[6]
Parasitic Species
Roundworms are known to infect other species of plants and animals around the world. In many farming communities there is a loss of crops due to the infections from roundworms. They can also affect other species, such as humans. Most of these infections come from species of roundworms, such as the hookworm, pinworm, and Guinea worm.[7]
A person can be infected by a hookworm by simply walking barefoot on contaminated soil.7 The hookworm goes into the small intestine of a person and releases larvae that matures and penetrates the human skin.[8] Most of these infections take place in tropical or subtropical climates.7 People who are infected sometime do not show symptoms, but other time they can suffer gastrointestinal symptoms. In some cases, people can suffer blood loss which lead to anemia, or protein loss. Though this infection is very serious, it is treatable with the correct medication.6
A Pinworm is a small, white parasite that infects the large intestine. This worm infects its host animal by feeding off of the hosts nutrients. Also, if an animal swallows a Pinworm egg, picked up from infected surface, it can be contaminated with Pinworms. Pinworms can be spread very easily just, but there are many treatments.[9]
The Guinea worm is a painful disease that affects a person when they drink contaminated water.[10] The larvae of a Guinea worm grow inside a person’s gut and connective tissues.7 The worm can grow to be over a metre long, and after a year the worm winds its way through the body. It then exits the body through the skin, leaving a painful blister behind.8
Nematoda Phylum Systematic
Adenophorea
Chromadoria
Spiruria
Diplogasteria
Above is the list of classes, sub-classes, and orders of the Nematoda, in a classical morphology-based classification system. As shown, there are five sub-classes and nineteen orders. In order to see which ones have plant-feeding genera, there are (*).[11]
Evolutionarily Successful
The Nematode is the most successful of several pseudocoelomate phyla. It is found in nearly every habitat including marine, freshwater, terrestrial, free living, and parasitic. They have populated every damp habitat that has been studied. Nematodes can be any of carnivores, herbivores or parasitic, and are found almost everywhere on earth. The Nematoda phylum is very abundant and ecologically important.[12]
External Links
Nematoda Virtual Library
Society of Nematologists
Roundworms/Nematodes & Human Parasitic Infestations
What are Nematodes?
Worm Learn
Nematodes/Roundworms of Man
Nematodes (Roundworms)
Roundworm Pictures/Nematode Pictures
Nematoda (Roundworms, Eelworms or Nematodes)
Nematodes (Roundworms)
Australasian Association of Nematologists
Gene clue to longevity uncovered
International Federation of Nematology Societies
Footnotes
[1] Mifflin, Houghton. The Free Dictionary. Houghton Mifflin Company, 2007. Web. 23 May. 2011.
[2] Nowicki, Stephen. Biology.” McDougal Littell, 2008. Page 716. Print.
[3] “Introduction to the Nematoda.” University of California Museum of Paleontology. Berkeley Natural History Museums. Web. 21 May. 2011
[4] “Complete Digestive Tract.” The University of Tennessee at Martin. 2011. Web. 22 May. 2011.
[5] “Hydrostatic Skeleton.” Encyclopedia Britannica. Encyclopedia Britannica, 2011. Web. 23 May. 2011.
[6] “Kingdom Animalia – Pseudocoelomates.” The Florida State University. Web. 22 May. 2011.
[7] Nowicki, Stephen. Biology.” McDougal Littell, 2008. Page 717. Print.
[8] “Parasites – Hookworm.” Centers for Disease Control and Prevention. 2 Nov. 2010. Web. 23 May. 2011
[9] “Pinworm Infection.” MedicineNet.com. MedicineNet, Inc. Web. 22 May. 2011
[10] “Real Lives.” Unite for Children. 2 Nov. 2004. Web. 23 May. 2011.
[11] Ferris, Howard. “Phylum Nematoda.” Nemaplex. University of California, 2 Dec. 2008. Web. 23 May. 2011.
[12] “Phyla Nematoda.” Biological Sciences. Ohio University, 2010. Web. 23 May. 2011.
Authors: Sydney McCully & Elyssa Erickson